358 



;^ooT/)GY 



SECT. 



number of diverticula or air-sacs which arc capable of being 

 inflated, causing an increase in the bulk of the animal which 



(loul)tless has an effect on assailants. 

 In the snake-like Lizards the right 

 lunof is larger than the left, and in 

 the AniphisbcBnians the latter is 

 entirely aborted. In the Snakes a 

 similar reduction or abortion of the 

 left lung is observable. In the 

 Crocodilia and Chelonia the lungs 

 ( I ^^ are of a more complex character. 



Fui. 1001.— Heart of Iiacerta muralis, ventral 

 view. A, A. auricles: Ap. jmlmuiiary artery; 

 As, As', sul)claviaii arteries ; ('(', pust-caval ; J. 

 jugular vein ; Ha, aortic arches (made up on 

 cither side of two embryonic arches, 1 and 2!) ; 

 V. ventricle ; Vp, pulm-->nary vein ; Vs, sub- 

 clavian vein. (From Wiedersheim's Comparative 

 Anatonvi.) 



being divided internally by septa 

 into a number of chambers. 



Organs of Circulation. — In the 



heart (Fig. lOUl) the sinus venosus 

 is always distinct, and is divided 

 into two parts b}^ a septum ; its 

 aperture of communication with the 

 right auricle is guarded by valves. 

 There are, as in the Amphibia, al- 

 ways two quite distinct auricles, the 

 right receiving the venous blood from 

 the body, the left the oxygenated blood brought from the lungs 

 by the pulmonary veins. But a vital point of difference between 



Fic. 1000. — L\nigs of Chamscleon. 

 T. tradiea. (l'"roni Wiedersheim's Com- 

 jiarative Anatom//.) 



